Why so expensive???

I asked MWEB earlier this week why is my fibre line that is VUMA so expensive, for 20Mps (download) line its R689 and with other providers is about R499 (download) for a 50Mps.

Despite talking to a supervisor and sending him emails no feedback has been given and also VUMA has the infrastructure in my area so I can't change.

I would like to know why are they so expensive and wat make them so special to justify this price.